Last night I noticed that my comet goldfish, Tiffy, was acting extremely weird. She was lying on the bottom of her tank and not really moving. I decided to "wait and see" and left her overnight, though I doubted that she would survive. This morning I woke up and she was still alive, but looking worse. Her gills are now barely moving. Please help me, I've become very attached to this fish and don't want to lose her.

Housing
What size is your tank? 10 gallons. I know it is too small, but I keep the parameters in check and I plan to upgrade very soon.
What temperature is your tank? Around 72-75ºF.
Does your tank have a filter? Yes. It has a tetra whisper HOB filter. It is cycled.
Does your tank have an air stone or other type of aeration? Nope.
Is your tank heated? Nope.
What tank mates does your fish live with? One greater pond snail.

Food
What type of food do you feed your fish? Tetra goldfish flakes.
How often do you feed your fish? Once daily.

Maintenance
How often do you perform a water change? About every 2 weeks, but I keep an eye on the parameters to make sure they are OK.
What percentage of the water do you change when you perform a water change? 50%
What type of additives do you add to the water when you perform a water change? Seachem Prime.

Water Parameters:
Have you tested your water? If so, what are the following parameters?

Symptoms and Treatment
How has your fish's appearance changed? Clamped fins, minimal gill movement.
How has your fish's behavior changed?Sitting on bottom of tank, not reallly swimming around, lethargic.
When did you start noticing the symptoms? Last night.
Have you started treating your fish? Nope.
Does your fish have any history of being ill? No.
How old is your fish (approximately)? I have no idea. She was a feeder fish at PetSmart. I have had her about 3 years.

Please help me! I really need to know what to do, this is my favorite goldfish!!

Hello! I'm a former fishkeeper and bettafish.com-er with a rekindled interest in the betta hobby. I don't have any bettas currently, but I'm brushing up on my fishkeeping knowledge with the intention of eventually bringing home another finned friend. ^_^

Hello! I'm a former fishkeeper and bettafish.com-er with a rekindled interest in the betta hobby. I don't have any bettas currently, but I'm brushing up on my fishkeeping knowledge with the intention of eventually bringing home another finned friend. ^_^

You certainly need to do large water changes more often. Weekly at least and bi-weekly if you can.

Jen brought up a good point. A three-year old goldfish that still fits in a 10 gal tank is stunted. Stunted fish live shorter lives and are more prone to ailments from things that wouldn't normally affect them. Without a picture, I would guess that he is succumbing to the high levels of nitrate and they are hitting him harder than normal because of his stunted condition. Really the only cure is a large tank with larger water changes. He's a comet so a pond is honestly best, but seeing as he is stunted, a 55 gal would suffice.

Hello! I'm a former fishkeeper and bettafish.com-er with a rekindled interest in the betta hobby. I don't have any bettas currently, but I'm brushing up on my fishkeeping knowledge with the intention of eventually bringing home another finned friend. ^_^

In a normal tropical tank, we strive for nitrate readings below 10ppm. Most goldfish tanks strive for below 20ppm. 40ppm is the max it should be allowed to get to in a goldfish tank. I know goldfish keepers who do 70% to 80% weekly water changes to keep it that low.

Hello! I'm a former fishkeeper and bettafish.com-er with a rekindled interest in the betta hobby. I don't have any bettas currently, but I'm brushing up on my fishkeeping knowledge with the intention of eventually bringing home another finned friend. ^_^

Hello! I'm a former fishkeeper and bettafish.com-er with a rekindled interest in the betta hobby. I don't have any bettas currently, but I'm brushing up on my fishkeeping knowledge with the intention of eventually bringing home another finned friend. ^_^